Pyridine-bis-(hydroxyaryl ethers) and derivatives thereof

ABSTRACT

Title products are described which are useful intermediates for the production of synthetic resins such as saturated and unsaturated polyester resins, polycarbonates and epoxy resins and which are prepared by reacting 2,6-dichloropyridine with a dialkali phenolate in the molar ratio of approximately 1:2 in the presence of a polar organic solvent at about 60* to about 180*C and acidifying the reaction mixture.

United States Patent 1 Darsow et a1.

[54] PYRIDINE-BIS-(IIYDROXYARYL ETHERS) AND DERIVATIVES THEREOF [75] Inventors: Gerhard Darsow; Hermann Schnell,

both of Krefeld-Verdingen, Germany [73] Assignee: Bayer Aktiengesellschaft, Leverkusen, Germany [22] Filed: June 29, 1970 [21] Appl. No.: 51,018

[30] Foreign Application Priority Data July 10, 1969 Germany ..P 19 34 889.1

[52] US. Cl. ..260/297 R, 260/47, 260/75, 260/294.8 F, 260/294.8 G, 260/297 B [S 1] Int. Cl. ..C07d 31/30 [58] Field of Search ..260/297 R [5 6] References Cited FOREIGN PATENTS OR APPLICATIONS 1,527,714 6/1968 France ..260/297 1 Feb. 13,1973

OTHER PUBLICATIONS Fieser and Fieser, Advanced Organic Chemistry, Reinhold Publishers, Pages 113, 306 (196]) OD 251 P52: C.4

Primary Examiner-Alan L. Rotman Attorney-Connolly and Hutz [5 7] ABSTRACT Title products are described which are useful intermediates for the production of synthetic resins such as saturated and unsaturated polyester resins, polycarbonates and epoxy resins and which are prepared by reacting 2,6-dichloropyridine with a dialkali phenolate in the molar ratio of approximately 1:2 in the presence of a polar organic solvent at about 60 to about 180C and acidifying the reaction mixture.

3 Claims, No Drawings PYRlDINE-BlS-(HYDROXYARYL ETHERS) AND DERIVATIVES THEREOF y riap hthalenes as well as bis-phenols of the formula IV The subject matter of the invention is novel pyridinebis-(hydroxyaryl ethers) of the formula I wherein Ar denotes phenylene, naphthylene, diphenylene or a polynuclear aromatic radial of the formula ll melt between about SO'C and about 230C and are,

soluble in solvents such as dimethyl sulphoxide, dimethyl formamide and dioxan. As dihydroxy compounds, they can serve, according to known processes, for the preparation of synthetic resins cg. polycarbonates, epoxy resins and unsaturated polyester resins the properties of which are modified by the incorporation of the pyridine ring; they can readily be dyed e.g. with acid dyestuffs. Thus polycarbonates may be produced by reacting the pyridine-bis-hydroxyaryl ethers, optionally in admixture with other dehydric phenoles, with diphenyl carbonate in the melt or by reacting the corresponding alkali metal diphenolates with phosgen in a mixture of water and methylene chloride. Unsaturated polyesters may be prepared by reacting the pyridine-bis-hydroxyaryl ethers with, for example, maleic acid anhydride or by reacting aqueous solutions of the alkali metal diphenolates with unsaturated dicarboxylic acid dichlorides while epoxy resins may be obtained by reacting the pyridine-bis-hydroxyaryl ethers with epichlorhydrine and hardening the so obtained epoxides with acids or amines. Said resins per se are well known to be plastics very useful for many technical purposes in the plastic field.

The new substances can, according to the invention, be prepared by reacting l mole of 2,6-dichloropyridinc with about 2 moles of a dialkali metal phenolate of the formula lll MeO Ar OMe I" wherein Me denotes an alkali metal in a polar organic solvent at temperatures between about 60C and about 180C, preferably between about 90 and about 160C, and

acidifying the reaction mixture.

wherein Z denotes a bivalent aliphatic, cycloaliphatic or araliphatic radical with one to eight C atoms or O-, S- --S()--, SO or CO-.

Examples of such bis-phenols are: bis-(4-hydroxyphenyl)-methane, l, l bis-(4-hydroxyphenyl cyclohexane, bis-(4-hydroxyphenyl)-phenylmethane, 4,4'-dihyelroxydiphenyl ether, sulphide and sulphoxide, 4,4-dihydroxybenzophenone, but particularly 2,2-bis- (4-hydroxyphenyl)-propane and 4,4'-dihydroxydiphenylsulphone.

Besides the hydroxyl groups, the aromatic nuclei may bear additional substituents, e.g. alkyl and alkoxy groups with one to four C atoms as well as halogen atoms, with the restriction that these substituents do not affect the reaction possibility of the hydroxyl groups by steric or other hindrance.

As cations for the diphenolates, those of the metals of the first main group of the periodic system are suitable. Preferably, the sodium and the potassium salts are used.

Of suitable polar organic solvents, there are mentioned for example diethyl sulphoxide, dimethylsulphone, diethylsulphone, diisopropylsulphone and tetramethylsulphone, but preferably dimethyl sulphoxide (DMSO).

The dialkali metal salts of the diphenols can be prepared according to known methods before the reaction proper by reacting the diphenol concerned in an inert organic solvent with the appropriate alkali metal, alkali metal alcoholate or alkali metal hydroxide, and subsequently distilling off the solvent with the alcohol or water which may have been liberated during the salt formation.

It is, however, simpler, and more expedient for the ensuing condensation reaction, to prepare in situ the dialkali metal phenolates concerned by causing the salt fonnation and the condensation reaction with 2,6- dichloropyridine in the presence of the polar solvent to proceed simultaneously or successively.

For this purpose, molar amounts of 2,6- dichloropyridine are dissolved with approximately twofold molar amounts of diphenol in a sufficient amount of the polar solvent, the stoichiometric amount of alkali metal hydroxide is added in solid form or as concent'rated aqueous solution and heating is effected under inert gas, e.g. nitrogen, gradually to reaction temperature. The reaction time is then, according to the reaction temperature and the water content of the mixture, about 1% 8 hours. After cooling, the reaction mixture is mixed with acidified water, whereupon the reaction product precipitates and can be separated. Impurities can be removed if desired by re-precipitation, washing out or re-crystallization from a suitable solvent.

To attain high yields and to shorten the reaction time, it may be favorable, in the condensation of the dialkali metal phenolates with 2,6-dichloropyridine, to

keep the water content of the reaction mixture low. For EXAMPLE 2 this purpose, the diphenol is dissolved in a sufficient amount of the polar solvent, the stoichiometric amount 2,6-bis-[(4'-hydroxy)-diphenoxy]-pyridine of alkali metal hydroxide is added in solid form or as 111.7 g (0.6 mole) 4,4-dihydroxydiphenyl and 48.0 concentrated aqueous solution, and the mixture is 5 g (1.2 moles) NaOH, dissolved in 50 ml of water, are heated for some time, e.g. 2 6 hours, under inert gas dissolved in 500 m1 dimethyl sulphoxide, with stirring to about 100 to about 150C and, during this, the and heating to 80C. 44.4 g (0.3 mole) 2,6- water present and the water liberated during phenolate dichloropyridine are added to the clear solution at formation is substantially distilled off from-the mixture, 40C and the reaction mixture is heated to 130-150C expediently with the conjoint use of an entraining for 7 hours. After cooling, the reaction product obagent, such as benzene, toluene, xylene or tained is precipitated by pouring into acidified water.

chlorobenzene. The 2,6-dichloropyridine is sub- After filtration, reprecipitation once from dilute solusequently added, whereupon the condensation reaction of Sodium hydroxide, Washing neutral and y g. a

proper takes place by heating, e.g. for 7% 5 hours, to yield of 1 14 g is Obtainedthe reaction temperatures i d If the product is colored, it can be recrystallized from Another simple m th d to b t i ll remove h a dimethyl formamide-water mixture or from a dioxanwater from the reaction mixture consists in dissolving water mixture- The White Powder melts at 2070-21 the diphenol and the alkali metal hydroxide, with heating, in a sufficient amount of the polar organic solvent 25 M Elementary analysis:C H O N Molecular weight and subsequently, before the addition of 2,6- dichloropyridine, to distil off about l020 percent by volume of the polar solvent, expediently under gfi 779 47 I43 31 Cale 447 5 vacuum. The water distils azeotropically with the parfound 7717 47 14:4 3:! found 44) tial amount of polar solvent from the reaction mixture. The 2,6-dichloropyridine is then added, whereupon, with further heating, condensation sets in. What we claim is:

EXA 1 l. Pyridine-bis-hydroxyarylethers of the formula C TI 136.97 g (0.6 mole) 2,2-bis-(4-hydroxyphenyl)- 45 wherein Ar is phenylene, naphthylene, diphenylene or propane and 48 g (1.2 moles) sodium hydroxide are aradicalofthe formula dissolved in 500 ml dimethyl sulphoxide by heating under an inert gas atmosphere (nitrogen). 44.4 g (0.3 mole) 2,6-dichloropyridine are added to the clear solution at 60C, and heating to l 10130C is effected for 50 Q n 6 hours. After cooling, the reaction product obtained is precipitated as snow-white powder by pouring into acidified water. After filtration, washing neutral and herein Z is alkylene, cycloalkylene or aralkylene haydrying, a yield of 144 g is obtained. i one m i h C atoms or 0 Minor higher-condensed components can be 2, 2 6-bi [4 4 h d h removed by re-precipitation from dilute solution of idi sodium hydroxide. The product melts at 6668C. 3. 2,6-bis[(4'-hydroxy )-diphenoxy l-pyridine. Elementary analysis: C H O N Molecular weight CMHMON calc. 78.0 6.3 12.1 2.1 calc. 531.7

found 77.9 6.2 12.3 2.6 found. 515 

1. Pyridine-bis-hydroxyarylethers of the formula wherein Ar is phenylene, naphthylene, diphenylene or a radical of the formula wherein Z is alkylene, cycloalkylene or aralkylene having one to eight C atoms or -O-.
 2. 2,6-bis-(4-(4-hydroxy-phenyl-isopropyl)-phenoxy)-pyridine. 